In the hearing instruments industry one of the primary goals is to make hearing instruments of small size while still maintaining good electroacoustic performance and operability giving good user friendliness and satisfaction. Technical performance data comprise such as sensitivity, stability, compactness, robustness and insensitivity to electromagnetic interference and to other external and environmental conditions. In the past, several attempts have been made to make microphones smaller while still maintaining good technical performance data.
EP 561 566 discloses a solid state condenser microphone having a transducer chip and, on the same chip, an electronic circuit and a cavity forming an opening or sound inlet for the transducer. The techniques and processes for manufacturing such electronic circuitry are quite different from the techniques and processes used in manufacturing the transducer elements. Consequently a chip having both an electronic circuit and an opening therein requires two (or possibly more) separate stages of production, usually at different facilities.